A live chronophotograph, seen from behind the subject: a black cat climbs a flight of stone steps in a night alley, and its past moments stay drawn as pale cats along the steps, with the present moment highlighted. The climb loops on its own. Scrolling down draws the camera back until the whole plate is in view, then carries the climb to its last frame before the page moves on; scrolling up reverses it. A pinch, or the plus and minus keys, bring the camera closer or farther. The scene is synthetic.

Plate 4D-002 Cat, ascending stairs.

A synthetic subject: ··· frames, every one kept on one plate.

4D.OS 1.0

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00:00:00 source

Sequence 12 of ··· exposures

    Animal locomotion. Plate 4D-002.

    00:00:00 HOLD 0.00×

    Plate 4D-002

    Drag this card across the plate: every position it passes stays exposed.

    Every moment,
    one plate.

    In 1912 Marcel Duchamp painted a figure descending a staircase with every step at once, after the chronophotographs of Marey. This desktop runs it the other way, live: a black cat climbs ten steps, and nothing moves away. Every instant of the climb stays where and when it happened.

    Plate I. Two dimensions, plus time.

    A glider from Conway’s Game of Life. Each generation is a flat grid; stack the generations and the glider stops moving and becomes a staircase in space.

    Plate II. From a film to a plate.

    1. A video

      Ordinary 2D frames from a single moving camera.

    2. 3D, one frame at a time

      Every frame becomes its own cloud of points, with the camera that saw it.

    3. Left where and when it happened

      Nothing is merged or averaged. Each frame stays at its place and its instant.

    The subject on these plates is synthetic: a low-poly cat by J-Toastie (CC-BY 3.0), animated by us and sampled into points frame by frame, standing in for a real reconstruction.

    Plate III. From the side.

    The same climb, seen side-on like a Marey plate. One exposure every second, climbing step by step.

    Plate IV. Measurements.

    Exposures
    ···
    Duration
    ···
    Frame rate
    ···
    Moving points
    ···
    Still points
    ···
    Weight on disk
    ···

    Read from the plate currently loaded, not typed by hand.

    Plate V. Subjects.

    Plate VI. Questions.

    Is this a video?

    No. It is a scene of points drawn live in your browser. Every frame of the original motion is kept, so the whole journey can be seen at once and walked through in any direction.

    Why does it look like an old screen?

    The picture is rendered at a fraction of your screen’s resolution and reduced to a small palette with ordered dithering, live, every frame. Switch the monitor to Millions to see the scene underneath.

    Is the cat real?

    Not yet. This plate uses a synthetic subject so the desktop can be built and measured before real captures exist.

    What do the keys do?

    Space holds or resumes. J rewinds, K holds, L plays forward; press J or L again to go faster. The arrow keys step one frame, and + and − bring the camera closer or draw it back while the climb loops. Page Down opens the plate and carries on down the page.